Functional Applications of Lignocellulolytic Enzymes in the Fruit and Vegetable Processing Industries

Cellulose, hemicellulose, pectin (carbohydrate), and lignin (noncarbohydrate) polymers are the main substrates of lignocellulose‐degrading enzymes. They are present in large amounts in the primary cell wall and dietary fibers of major fruits and vegetables. During processing of fruits and vegetables to the corresponding final food products, lignocellulosic substrates are hydrolyzed by different lignocellulolytic enzymes. Currently, lignocellulolytic enzymes such as cellulases, xylanases, pectinases, and laccases are extensively used during the processing of fruits and vegetables, in applications like texturizing and flavoring of products in the food industries. The present article provides an updated overview of functional applications of lignocellulolytic enzymes in the juice processing, oil extraction, and alcoholic beverage processing industries. Extensive use of lignocellulolytic enzymes in different food processing industries not only accelerates the production rates but also improves product quality. It is also possible to ensure the efficient use of fruits and vegetables globally by employing lignocellulolytic enzymes in the corresponding processing industries to convert them into food commodities, which will not only raise their economic value in the global market but also increase food availability, which will help mitigate nutritional problems worldwide.     

Relationship Between Extracellular Cellulase,Pectinase and Xylanase Activity of Isolated Aspergillus oryzae Strains Grown on Koji and the Umami-Tasting Amino Acid Content of Soy Sauce

We compared the koji-based extracellular carboxymethylcellulases (CM-cellulase), pectinases and xylanases of four Aspergillus oryzae isolates from soy sauce koji, A1, PRB-1 (A2), A3 and A4, with Aspergillus oryzae AS3.951 (A5) via enzyme assays and zymography and determined their correlation to the content of umami-tasting amino acids in high-salt diluted-solid state growth stage leading to soy sauce. In A2 koji, xylanase had the highest activity (28.75 U/g dry weight). Zymogram analysis revealed two different bands of CM-cellulase activity (termed Cel-1 and Cel-2) and one band of pectinase activity (Pec-1) in all koji samples. The intensity of these bands was comparable among all five strains. Interestingly, the same analysis revealed six different xylanase activity bands (termed Xyl-1 to Xyl-6) in all koji samples. After 60 days of cultivation, the free amino acid concentration was highest in soy sauce generated by A4 at 6709.41 mg/100 ml and contained 1690.82 mg/100 ml umami-tasting amino acids (including glutamic acid and aspartic acid), followed by soy sauce generated by A2. Pearson’s coefficient analysis indicated that Xyl-1 and Xyl-2 activities were positively associated with the umami-tasting amino acid content of soy sauce. In conclusion, these data suggested that the xylanases Xyl-1 and Xyl-2 in koji could be important contributors to the umami taste formation of soy sauce.     

黑曲霉产纤维素酶菌种的激光选育

报道了以黑曲霉为出发菌株．采用铜蒸气激光诱变处理．筛选纤维素酶高产菌株．获得了４株高产的突变菌株，用稻草麸皮固体培养基，２８℃发酵培养４天．每克湿曲的最高酶活：ＣＭＣ酶活（Ｃｘ）为２８３９ｍｇ葡萄糖／ｇ·ｈ、滤纸酶活（ＣＬ）为２９９ｍｇ葡萄糖／ｇ·ｈ，β－葡萄糖苷酶活为１０９１ｍｇ葡萄糖／ｇ·ｈ。并且对突变株Ｎｏ．８号菌株的菌落形态、生长发育及发酵周期等变异性状、纤维素酶高产性状的稳定性等方面都进行了深入的测试和分析对比．从试验结果表明．激光诱变技术方便实用．效果明显．是一种新的微生物诱变育种的理想方法之一。     

纤维素酶固态发酵环境扫描电镜观察

纤维素酶压力脉动固态发酵周期（60h）比传统固态发酵周期缩短1/3，酶活（2036IU/g）比传统酶活（10.82IU/g）提高了一倍。利用环境扫描电镜观察压力脉动固态发酵与传统固态发酵微观动态过程表明，压力脉动固态培养的料层（9.0cm厚）上中下微生物生长状况均匀一致，且疏松；而传统固态发酵的料层中部几乎没有菌体生长。并且发现微生物产孢初期，其产酶即停止，压力脉动固态发酵在72h开始产生孢子，其产酶达到最高峰；而传统发酵在96h才出现大量的孢子。     

产纤维素酶细胞固定化研究

用海藻酸钙凝胶包埋法制备木霉固定化细胞,研究了固定化条件和培养条件对固定化细胞稳定性及产纤维素酶的影响,初步确定了产纤维素酶木霉细胞的固定化方法。     

复合纤维素酶对杨木SGW浆纤维素结晶度和微晶体尺寸的影响

在杨木SGW浆酶改性过程中,伴随酶解的进行,纤维素结晶度缓慢增加。在酶解初期,浆的纤维素结晶度增加的幅度相对较大;在酶解后期,浆的纤维素结晶度增幅较小,并趋于一稳定值。另外,伴随酶解的进行,酶解作用使得纤维微晶体尺寸逐渐减小。这说明杨木SGW浆酶改性主要发生在纤维表面的半纤维素存在区域和纤维素的无定形区域。伴随酶改性的进行,酶改性是从纤维表面逐渐向内扩散,在纤维表面产生“剥皮效应”。     

杨木SGW浆复合纤维素酶改性的研究

对用复合纤维素酶处理杨木 Ｓ Ｇ Ｗ 浆, 改善浆的滤水性能和抄造性能进行了研究。结果表明, 用复合纤维素酶对杨木 Ｓ Ｇ Ｗ 浆进行处理, 在保持浆原强度的情况下, 浆的滤水性能有较明显的改善。     

酶在生物质转化为燃料酒精中的应用

生物质作为可以再生的能源广泛存在于自然界中。应用酶水解技术处理生物质所制造的燃料酒精可以部分替代石油,生物质还可以被进一步转化成其他的化学产品及生物化学品。预处理过程和纤维素酶成本的降低,纤维素酶效率的提高是生产生物质酒精及其他化学产品的关键。文中介绍了该转化过程的关键技术及其发展进程和最新进展。